Method of cementing carbon articles.



J. BROWN. METHOD or CEMENTING CARBON ARTICLES.

APPLICATION FILED JUNE 6| 1912. v

Patented Oct. 26, 1915.

2 SHEETSSHEET m 0 Q o o o m 2 Ak\ J m mHw H 6a m EMP ZZI; U m n .3 m n B r L E n w mm m m Q o n M N o ml .HMELH INVENTOR JOHN W. BROWN ATTORNEY J. W- BROWN.

METHOD OF CEMENTING CARBON ARTICLES.

I APPLIC'ATION FILED JUNE 1912. 11; 15,1?L Patented 00t.26,1915.

2 SHEETS-SHEET 2.

WITNESSES INVENTOR JOHN W,BRDWN 4 ORALL Qp/w ATTORNEY JOHN-T. BROWN, OF LAKEWOOD, OHIO, ASSIGNOR TO NATIONAL CARBON COMPANY,

OF CLEVELAND, OHIO, A CORPORATION OF NEW JERSEY.

METHOD OF CEMENTING CARBON ARTICLES.

meairr.

[0 all tvkom it may concern Be it known that I, JOHN W. BROWN, a resident of Lakewood, in the county of Cuyahoga, in the State of Ohio, have in vented new and useful Improvements in the Method of Cementing Carbon Articles, of

which the following is a-clea-r and exact description.

This invention relates to the treatment of carbon articles. y D

'One object of the inventlon 15; to close seams and. laminations in carbon. articles and cement them togetherso that the defects no longer exist.

Another ob ect is to compress carbon articles and cement together the surfaces of the pores and cells originally therein.

Other objects will appear in the appended description.

. The term carbon used 1n this application is not intended to be specific, but to include Baked carbon articles are somewhat porous due to the escape of volatile matter in the baking process. This is objectionable as the resistance is therefore higher than it should be and in the case of electrolytic anodes the porosity causes the rapid deterioration of the anode, due for the one thing to the increased surface exposed to the attack of the electrolyte. The mechani cal strength of the article is also impaired.

I have discovered a. process whereby the articles can be made more dense by sub stantially relieving them of 'their porous nature. As described in my other application above referred to I have found that when carbon articles are heated to a very high temperature they become semi-plastic and the carbon material can be made to flow by applying pressure thereto. This characteristic of carbon must not be con-. fused with that due to uncoked binder. It is well known that green carbon articles are dense and solid under ordinary temperatures, but become plastic under pressure,

Specification of Letters Patent.

Application filed une's, 1912. Serial No. 702,120.

Patented Oct. 26, was.

especially when heated slightly to soften the uncoked binder. The plasticity of carbon that I refer to is that of a baked carbon artlcle with the binder coked. When heated 'in accordance with my process, the carbon particlesthemselves become plastic. A carbon article can therefore be compressed and made" more dense by heating it till it becomes plastic and then applying pressure or by putting pressure on "before the article ,becomes plastic as will be later explained. I have'further found that ifa porous article be first impregnated with tar, oil or other blndlng material before it is heated and compressed, the'surfa'ces of each collapsed pore adhere firmly together and a dense mass is produced with each particle joined to adjacent particles. This means that the resistivitywill be lowered and the mechanical strength increased.

When carbon articles are graphitized by ,the Acheson process many of them develop seams and laminations. .The percentage of the defective articles sometimes runs as high as 75% of the furnace charge. These were formerly utilized as scrap. The .de fects can readily be corrected by my invent tion so'that-a great saving results.

In my other application referred to I disclose a way to compress defective articles-so that fissures and seamsare eliminated. Theuresulting product still has the separated surfaces, as theylwill not firmly unite,

and for most purposes is as good as if the surfaces werefirmly united. By first treating the articles with tar, oil or other binder as previously disclosed'herein, the surfaces will adhere together so that the compressed rent through the articles to be treated;

though the same results at a lesser degree maybe obtained by heating. The method is not limited to any specific apparatus, but could be carried out by many difierent forms of appliances. However, for the purpose of completely disclosing the method, I

have shown on the drawings a type of electrical apparatus well'suited for the purpose.

In the drawings: Figure l is a side elevation of the apparatus which maybe called a furnace, although it has no resemblance to the usual type of furnace. Fig. 2 is a top view of the same. Fig. 3 is a sectional view taken on the'line AA ofFig. 1 look-- ing in the direction indicated by the arrows.

' Fig. 4 is a view of the box containing the articles to be treated showing them clamped in place Fig. 5 is a view of the device used to place the carbon articles in the box of Fig. 4. Fig. 6 is a view of the formshown in Fig. 5 before the articles are placed thereing made of angle irons. At the top there are two angle irons 1 and 2 joined to similar irons 3 and 4 at the ends The angle irons may be joined together'ig anyway, but I have shown them as being mitered so as to form a neat joint, and riveted or jointed tp1 four posts 5, 6, 7 and 8. -In order to make t e braced by the braces 10, 11, 12 and 13. The lower frame, one member of which 14 is shown in Fig. 1 is identical in all respects to the upper frame. I have shown two metal supports 15 and 16 fastened to the lower frame at the middle. The legs or supports of the furnace may be bolted to posts or pillars, or they may be simply fastened to a table tr floor as desired. The lower frame is preferably covered with a layer of some nonconducting substance 16' such as transite board, composed of asbestos and cement. Such material forms a very strong board and will answer well the purpose of this arrangement.

By referring to Fig. 3 and Fig. 7,it will be seen that the member 17 is joined to the corner posts 5 and 6, and insulated therefrom. The insulation may consist of fiber board or any other well known suitable nonconducting material. A screw 18 connected to the electrode 19 passes through the,

threaded opening in the member 17. The screw is revolved by any means, but I have shown a wheel 20 which is insulated therefrom in any way. A good way to do this trode 19, and is held in place by two plates frame more rigid the irons may be- 22 and 23. 'In order to make good electrical connection with the electrode, two copper plates 24 and 25 are clamped by the plates 22 and 23 against the electrode. The

.plates are held firmly by the bolts 26, 27,

.37 bearing in a circular cavity in the plate 21. The plate 38, having a corresponding cavity anda hole for the )assage therethrough of the screw 18, is astened to the plate 21 by appropriate means such as a screw 39 and a screw 40. Lugs 41 and 42 on the copper plates 24 and 25 are;provided so that conducting cables can be connected thereto. These are marked :1: and on the drawings to indicate that they are the terminals. The electrode is held in place and properly guided by pairs of straps 43 and 44joined together by pairs of rollers 45 and 46 above and below the electrode. The rollers permit of the electrode being moved back and forth bylmeans of the operating wheel 20 with minimum friction. The straps are secured to the board 16 by appropriate screws or bolts. The rollers 45, 46 and the straps 43, 44 could be formed of iron, but since they would form a closed magnetic circuit around the electrode, the hysteresis loss might be high enough to cause trouble. If either the straps or the rollers were made of non-magnetic metal this trouble would be avoided. The trouble could also be obviated by using some material such as transite or fiber for this purpose.

The right hand side of the furnace in all its details is exactly identical with that of the left hand which has just been fully described so that it is unnecessary to allude to it in particular. trode and its connections are numbered similarly to those on the right. 2

Two iron rails 47 and 48 are fastened to the board 16 to serve as supports for the box which contains the articles to be heated and compressed. The box shown in Fig. 4 consists of two sides 49 and 50 joined to two end pieces 51 and 52 and the bottom 53. These boards are preferably made of transite board or other materials that would serve the purpose equally as well. The box can be made stronger by means of angle irons 54 and 55 joined to the bottom and sides. End plates 56 and 57, 58 and 59 may be fastened to the corners where the sides join the ends in order to further strengthen the box. The strengthening irons used on The parts of the electhe box are not absolutely necessary, and in order not to render the showing confusing in Figs. 1 and 2, the box .is there shown without them.

I For apurpose to be later described twoscrews -and 61 are threaded through irons member 51 to press 56 and 57 and the against the conducting block 62. It is not necessary to have similar screws on the other end of the box, hence theconducting block 63 bears against the end member 52. The two end members 51 and 52 have openings therein to receive the two electrodes 19. The opening in the board 52 is not shown in Fig. 4, but it is identical with that in the end 51. In order to facilitate the placing of the brushes in the box 48, a device 64 shown in Fig. 6 may be used. This consists of two boards 65 and 66 fastened together to form an angle. These boards may be made of any materials, but wood is most convenient. Two slots 67 and 68 in these boards receive members 69 and 70 in a loose fit. Screws or .pins 71 and 72 passthrough slots in the members 69 and 70 and hold them in place. The use of the apparatus disclosed will now be given in detail. The articles to be heated and compressed are shown as blocks 73. These are placed side by side in the angled form 64 as shown in Fig. 5 with the cracks or laminations approximately perpendicular to the direction of the electrodes. 'By referring to Fig. 5, it will be noted that the end block 73 extends past the boards 65 and 66, and is substantially flush with the ends of the members 69 and 70. The device 64 and the brushes therein are taken by the operator and placed in the box 48 and held so that the center line of the brushes is approximately in line with the center line of the blocks 62 and 63, and then the screws 60 and 61 are manipulated forcing the block 62 against the column of carbon articles, which clamps them firmly together against the block 63. The members 69 and 70 slide in the slots 67 and 68, and permit the carbon blocks to be clamped in place without clamping the device 64 at the same time. The latter is then removed by the operator. If desired the box may be placed in the furnace and the current turned on without covering the articles with any cient charcoal should also be placed on top to cover well the carbon-blocks. The box 48 with the carbon articles and the heat insulating material. is then placed by the operator on the rails 47 and 48-of the furnace .use this scheme alone.

filled up with a proper amount of charcoal A bag .of

and slid into place in proper alinement with the two electrodes 19. The wheels 20 are then manipulated to push the electrodes through' the openings in blocks 62, 63 to press them against the' carbon articles and more firmly press thenr in contact withfeach other. The current i's-then turned on. The

current density may be any value, desired."

I have used current densities as high as 5000 amperes per squareinch. An average density of 1000 amperes per square inch is suflicient to make the carbon articles semiplastic in a very short time. The time required, of I pressure is applied before the current is turned on or after the articles begin to soften. I prefer, however, to put the full pressure on at the start. This is sufficient to compress the articles when they become plastic. When the process is complete the current is turned off and the electrodes are drawn from the opening in the end plates of the box 48. The box is then removed and the contents dumped into a receptacle.

Another box can have been filled by the one operator or by others if more are needed, so that the furnace can be kept almost continually in operation. this process will no longer have laminations or seams. If it be broken up the pieces will show no' free surfaces existed;

While the use of the device 64 is very convenient in placing the carbon articles in place in the box 48, it is not necessary to The box could be and' then the articles could be placed in between the electrodes ontop of the charcoal. I prefer, however, to use the device 64.

The procedure for compressingarticles to make them more dense is the same asprevi'ously outlined though, of course, when the sole purpose is to increase the density the articles are treated regardless of whether they are free from flaws or have cracks or-laminations.

Having described my invention what I claim is: a

consists in impregnating it with acementing material, placlng it under pressure and passing an electrlc current therethrough, where- An article treated by 1. The method of compacting a baked carbon article with carbonaceous binder which- .by the particles flow and are cemented together. I 2. The method of compacting a baked carbon article with carbonaceous binder Y placing it under pressure and passing an which consists in impregnating it with tar,

electric current therethrough, whereby the particles flow and are cemented together.

3. The method of compacting a baked carbon article with carbonaceous binderuwhich consists in impregnating it with a'cementing material, heating the carbon and submitting it to pressure to cause the particles to flow and cement together.

4. The-method of compacting a baked carbonarticle with carbonaceous binder which consists iii-impregnating 1t with tarry materiaLheating the carbon and submitting it to pressure to cause the particles to flow and cement together. I

5. The method of eliminating seams and laminations in. a carbon article which consists in impregnating it with a tarry material, passing an electric current through it until the carbon becomes plastic and submitting it to pressure whereby the surfaces are cemented together.

'6. The method'of eliminating seams and rial, heating it to a high temperature until the carbon becomes plastic, and putting it under pressure'to cause the surfaces of the seams and laminations to join and be cemented together.

8. The method of elimiilating seams and laminations in a carbon i'ticle, which consists in impregnating it ith a cementing material, heating it to a high temperature until the carbon becomes plastic, and putting itunder pressure to cause the surfaces of'the seams and lamination's to join and be cemented together.

In testimony whereof I have hereunto v signed my name.

JOHN W. BROWN. Witnesses H. G. GROVER, I. J. AoAMs. 

